i want to ask how do we convert the contents of the array into a string and calculate the same value?

ex: 
const arr = [1,1,2,2,3,3,3,3]

If arr contain

values 1 = red,

values 2 = white,

values 3 = brown

**I have tried with the if else method but it doesn't work

my expected output was

red : 2 white : 2 brown : 4

can anyone help me? Thank you in advance